High Temperature Operating Life (HTOL) is one method of estimating the operating life of a product.
The High Temperature Operating Life (HTOL) or steady-state life test is performed to determine the reliability of devices under operation at high temperature conditions over an extended period of time. It consists of subjecting the parts to a specified bias or electrical stressing, for a specified amount of time, and at a specified high temperature, or in other words it is a long-term burn-in.
Unlike production burn-in which accelerates early life failures, HTOL testing is applied to assess the potential operating lifetimes of the sample population (hence the term ‘life test’). It is therefore mote concerned with acceleration of wear-out failures. As such, life tests should have sufficient durations to assure that the results are not due to early life failures or infant mortality.
A light emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting.
Light-emitting diodes are used in applications as diverse as replacements for aviation lighting, automotive lighting (in particular brake lamps, turn signals, and indicators) as well as in traffic signals. LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances.
Thermo-electric cooler (TEC) or thermoelectric cooling uses the Peltier effect to create a heat flux, between the junctions of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other side against the temperature gradient (from cold to hot, or from hot to cold), with consumption of electrical energy. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC). The Peltier device is a heat pump; when direct current runs through it, heat is moved from one side to the other. Therefore, it can be used either for heating or for cooling (refrigeration), although in practice the main application is cooling. It can also be used as a temperature controller that either heats or cools.
The thermoelectric cooling technology is far less commonly applied to refrigeration than, for example, vapor-compression refrigeration. The main advantages of a Peltier cooler (contrasted to a vapor-compression refrigerator) are its lack of moving parts or circulating liquid, mid its small size and flexible shape (form factor). Its main disadvantage is that it cannot simultaneously have low cost and high power efficiency. Many researchers and companies are trying to develop Peltier coolers that are both inexpensive and efficient.
A Peltier cooler is the opposite of a thermoelectric generator. In a Peltier cooler, electric power is used to generate a temperature difference between the two sides of the device, while in a thermoelectric generator; a temperature difference between the two sides is used to generate electric power. The operation of both is closely related (both are manifestations of the thermoelectric effect), and therefore the devices are generally constructed from similar materials using similar designs.
Device under test (DUT) in semiconductor testing refers to a specific die on a wafer or the resulting packaged part. Using a connection system, the part is connected to a manual or an automatic test equipment (ATE). The ATE then applies power to the part, supplies stimulus signals and then measures and evaluates the resulting outputs from the device. In this way, the ATE determines whether the particular device under test (DUT) is good or bad.
While in water form, the ATE connects to the individual DUT (die), using a set of microscopic needles (or probe card). Once the wafer is sa wed-off and the passing die are singulated, and assembled in a package, the ATE connects to the DUT (package) via sockets (sometimes called contactors). The DUT board is often connected to the ATE via a bed of nails of pogo pins.
The term device under test (DUT) is also used more generally within electronics to refer to any electronic assembly under test. For example, cell phones coming off of an assembly line may be given a final test in the same way as the individual die were earlier tested. Each cell phone under test is, briefly, the DUT.
A Proportional Integral Derivative (PID) controller or loop is a generic control feedback loop (controller) widely used in industrial control systems—a PID is the most commonly used feedback controller. A PID controller calculates an “error” value as the difference between a measured process variable and a desired setpoint. The controller attempts to minimize the error by adjusting the process control inputs.
The PID controller calculation (algorithm) involves three separate constant parameters, and is accordingly sometimes called three-term control: the Proportional, the Integral, and Derivative values, denoted by, P, I, and D, respectively. Heuristically, these values can be interpreted in terms of time; P depends on the present error, I on the accumulation of past errors, and D is a prediction of future errors, based on current rate of change. The weighted sum of these three actions is used to adjust the process via a control element; such as, the position of a control valve, or the power supplied to a heating element.
In the absence of knowledge of the underlying process, a PID controller is a good controller to use. By tuning the three parameters in the PID controller algorithm, the controller can provide control action designed for specific process requirements. The response of the controller can be described in terms of the responsiveness of the controller to an error, the degree to which the controller overshoots the set-point and the degree of system oscillation. It should also be noted that the use of the PID algorithm for control does not guarantee optimal control of the system or system stability.
Some applications may require using only one or two actions to provide the appropriate system control. This can be achieved, for example, by setting the other parameters to zero. A PID controller may be called a PI, PD, P or I controller in the absence of the respective control actions. PI controllers are fairly common, since derivative action is sensitive to measurement noise, whereas the absence of an integral term may prevent the system from reaching its target value due to the control action.
U.S. Pat. No. 5,973,050 (George H. Johnson, et al), the entire disclosure of which is incorporated herein by reference, discloses a composition of matter in which nanophase metal particles are effectively dispersed in a polymer matrix so that hitherto unattainable thermoelectric properties are attained. Preferred polymers and metals are taught. A method of making the composition of matter useful as a thermoelectric composite material using a conducting polymer matrix is disclosed as is a thermoelectric cooling/heating device which uses that composition.
U.S. Pat. No. 6,463,743 (Jacques Laliberte), the entire disclosure of which is incorporated herein by reference, discloses a modular thermoelectric cooling/heating unit which is installed through an opening in a wall separating first and second temperature zones. This modular thermoelectric cooling/heating unit comprises a thermoelectric device including a cold surface, a hot surface, and a cooling/heating member between an electrical power supply and the cold and hot surfaces. A heat conducting block has a proximal end for thermally contacting with a first one of the cold and hot surfaces, and a distal end. A first heatsink thermally contacts with a second one of the cold and hot surfaces, a second heatsink thermally contacts with the distal end of the heat conducting block, and a thermally insulated housing covers at least a portion of the heat conducting block between the proximal and distal ends of this block. In operation, the first heatsink is located in the first temperature zone, at least a portion of the heat conducting block; and the thermally insulated housing extend through the wall opening, and the second heatsink is located in the second temperature zone. The above described modular thermoelectric cooling/heating unit can be used in a modular cooling system for retrofit into an existing refrigeration unit.
U.S. Pat. No. 7,059,137 (William H. Childress), the entire disclosure of which is incorporated herein by reference, discloses an invention which uses electric current to either chill or warm air ambient air. The Portable Thermoelectric Cooling and Heating Device is composed of an array of thermoelectric units, a driving fan, a cold sink, a hot sink, air baffles and a cooling fan. The thermoelectric units are arranged in contact with the cold sink (cold side) and hot sink (hot side). Applying a current causes a temperature difference to develop between each side. The driving fan creates a pressure gradient is to pull air through the center of the cold sink. The cooling fan pulls air through an arrangement of baffles connected to the hot sink to help dissipate heat. The result is chilled or hot air, depending on the direction of the current. The invention allows for several improvements over current heating and air-conditioning systems; a simplified design without moving parts, elimination of the need for FREON, improved versatility and others.
U.S. Pat. No. 7,164,077 (Rama Venkatasubramanian), the entire disclosure of which is incorporated herein by reference, discloses a thermoelectric cooling and heating device including a substrate, a plurality of thermoelectric elements arranged on one side of the substrate and configured to perform at least one of selective heating and cooling such that each thermoelectric element includes a thermoelectric material, a Peltier contact contacting the thermoelectric material and forming under electrical current flow at least one of a heated junction and a cooled junction, and electrodes configured to provide current through the thermoelectric material and the Peltier contact. As such, the thermoelectric cooling and heating device selectively biases the thermoelectric elements to provide on one side of the thermoelectric device a grid of localized heated or cooled junctions.
U.S. Patent Publication No. 2002/0117747 (Mindaugas F. Dautartas, et al.), the entire disclosure of which is incorporated herein by reference, discloses a method and apparatus for supporting semiconductor devices on a flexible support which includes one or more thermoelectric cooling devices. The thermoelectric cooling devices, which include at least one pair of positively-doped and negatively-doped elements electrically coupled together, are positioned between a pair of flex panels. Each panel has connector sites at which connectors such as solder balls are located. Hie thermoelectric cooling devices may be arranged between the panels to create two or more device support areas having different temperature regimes. The thermoelectric cooling devices may be connected to the panels by placing the panels, connectors and thermoelectric cooling devices in a reflow chamber, exposing them to a reducing atmosphere, and heating to a temperature sufficient to reflow the connectors.
U.S. Patent Publication No. 2009/0188259 (Renato Colja, et al.), the entire disclosure of which is incorporated herein by reference, discloses an integrated thermoelectric cooling element and a positive temperature coefficient heating element are integrated into a single package. A heat sink is shared between the thermoelectric cooling element and the positive temperature coefficient.
This invention improves on the deficiencies of the prior art and provides an inventive system and a method for thermal control and management.